The big picture: Henri Cartier-Bresson in 1950s Moscow

Henri Cartier-Bresson's picture from Moscow was the front cover of Life magazine in early 1955. Photograph: Magnum

Cartier-Bresson sought to capture with his camera what he called decisive moments, coincidentally graceful arrangements of people or objects that other observers would have overlooked. He wandered through foreign cities like a libertine on the prowl, poised to take advantage of any opportunity for visual seduction. The taller soldier here, whose lips curl into a raffish smirk as he strides towards a possible conquest, might be a mirror-image of the invisible photographer. You can feel the frisson of sensual anticipation that accompanied the click of the shutter.

Cartier-Bresson was in Moscow to prepare a book recording the daily life of its population, and this image is heavy with documentary evidence about the grim Soviet experiment in regimenting civil society and reforming greedy human nature: the shabby clothes of the women or that battered case, the stoically shuffling queue for the trolley, the soldiers who should have had their minds on surveillance of another kind. The sky is webbed with wires, the pavement is stained. Does that topless column prop up a statue of Lenin exhorting the masses or Stalin terrorising them? Luckily the photograph decapitates it.

What's left, when you erase the political subtext, is a small Russian rite of spring that prematurely undermines communism. The men have no doubts about their paramilitary mission, and they wear their pantaloons, polished boots and rakishly angled caps as showy plumage, not a drab concession to uniformity. Pretending to look elsewhere, the women signal availability with disengaged, idling hands or arms meditatively crossed. The men are on the march; the women, their feet set with balletic elegance in positions of rest, know that all they need to do is wait. Lenin wanted to be an engineer of souls. Bodies, it's good to see, are not so easy to indoctrinate.